Topic 2: Background

Question 1

Explain neurotransmission

Answer 1

An action potential passes through the axon of the pre synaptic neurone, when the axon terminal is reached the action potential stimulates vesicles containing neurotransmitters to fuse with the membrane, the neurotransmitters are released into the synaptic cleft.

Receptors on the membrane of the post synaptic neurone absorb the neurotransmitters and the action potential continues through the post synaptic neurone

Question 2

Monoamine hypothesis of depression

Answer 2

Suggests depression is caused by low levels of monoamines; serotonin, noradrenaline and dopamine

Question 3

What are monoamines important for?

Answer 3

Regulating the function of the limbic system

Question 4

Serotonin’s in depression

Answer 4

Low levels

usually regulates the other monoamine neurotransmitters

Erratic brain functioning and thinking patterns happen because the other neurotransmitters are not stable.

Also responsible for: Mood, well being, stomach functioning and memory

Deficiency: Reduced appetite and low mood

Question 5

Noradrenaline’s role in depression

Answer 5

Present in the hypothalamus nd hippocampus and is responsible for heart rate, concentration, attention and alertness.

Deficiency: Irregular sleep patterns and a lack of energy

Question 6

Dopamine’s role in depression

Answer 6

Responsible for motivation, pleasure and reward.

Deficiency: Reduced attention and motivation, less interest in pleasure

Question 7

Jeffrey Meyer’s research into the biochemical influence in depression

Answer 7

17 Pxs
No antidepressants for 5 months
PET scans compared with 17 clinically normal people

Depressed Pxs had higher monoamine oxidase levels (monoamines broken down to quickly meaning there is less of them)

Question 8

The original dopamine hypothesis for schizophrenia

Answer 8

People with schizophrenia produce an excessive amount of dopamine in the brain (especially the limbic system)

Question 9

The revised dopamine hypothesis for schizophrenia

Answer 9

Excessive amount of dopamine receptors at the post synaptic neurone and that these receptors are more sensitive than they should be . (D2 receptors)

Question 10

What are positive symptoms of schizophrenia linked to?

Answer 10

hypofunction (too much dopamine) in the mesolimbic pathway.

Question 11

What is the mesolimbic pathway responsible for?

Answer 11

Motivation, emotion and reward

Question 12

What are negative symptoms of schizophrenia linked to?

Answer 12

Erratic dopamine function in the mesocortical pathway.

Question 13

What is the mesocortical pathway responsible for?

Answer 13

mental control and self regulation

Question 14

Philip Seeman’s research into schizophrenia

Answer 14

Drugs that increase dopamine increase positive symptoms

Antipsychotic drugs reduce symptoms of schizophrenia

Post mortems of schizophrenic brains show higher densities of D2 receptors than neurotypical brains

Question 15

What does “localisation” mean?

Answer 15

Particular areas of the brain do particular jobs

Question 16

Role of the prefrontal cortex

Answer 16

Behavioural control

Damage = less self control and impaired emotional processing

Question 17

Role of the limbic system

Answer 17

Processing emotions and stress responses

Question 18

Role of the amygdala

Answer 18

Feelings of fear and stores emotional memories

Question 19

Role of the hippocampus

Answer 19

Processing memories, responding to stress hormones.

Question 20

The amygdala’s role in depression

Answer 20

Higher activity levels

Increased activity when shown negative stimuli, decreased activity when shown positive stimuli

Question 21

The hippocampus’ role in depression

Answer 21

Smaller (up to 20%)

Explains why depressed people process emotionally charged memories dysfunctionally

Question 22

Yvette Sheline’s research into brain abnormality as an explanation for depression

Answer 22

fMRI
11Pxs, 11 control

Amygdala more active in depressed (especially when shown images expressing fear)

Antidepressants given = reduction in activity

Question 23

Brain abnormalities in schizophrenia

Answer 23

Enlarged ventricles
Reduced grey matter
Small brain size

Question 24

Reduced grey matter in the temporal lobes, frontal lobes and thalamus leads to…

Answer 24

Temporal lobes = auditory hallucinations

Frontal lobes = Incoherent speech and delusions

Thalamus = auditory and verbal hallucinations

Question 25

Genetic Explanation of depression: Family studies

Answer 25

Gottesman

Child has an increased risk of developing bipolar disorder if one parent has that or another condition.

One parent with bipolar = 4.4% chance of the child having bipolar

Compared to 0.63% chance for general population

Question 26

Genetic Explanation for depression: Twin studies

Answer 26

Concordance rates:
MZ = 30-50%
DZ = 12-40%

Suggest that depression has a significant causative genetic component

Question 27

Genetic Explanation for depression: Adoption studies

Answer 27

less consistent

Paul Wender et al (1986) found that the biological relatives of a depressed adoptee were 8x more likely than adoptive relatives to also have depression

Question 28

Genetic Explanation for depression: Association studies

Answer 28

People who have a part of short alleles on the hSERT gene are less resilient to stress.

Alan Ogilvie (1996) compared hSERT gene is 39 people with depression and 193 people from the general population.

Found high occurrence of short alleles in the group with depression

Question 29

Genetic Explanation of schizophrenia: Family studies

Answer 29

1% risk for general population
10x greater risk for the first degree relatives of a person with schizophrenia (Brian Riley & Ken Kendler 2005)

Gottesman:
A child with one parent with schizophrenia has a 7% risk of being diagnosed with the same disorder.

Question 30

Genetic Explanation of schizophrenia: Twin studies

Answer 30

Concordance:
MZ twins = 46-53%
DZ twins = 15%

Greater concordance for MZ twins implies a substantial genetic component to schizophrenia

(Stephen Glatt 2008)

Question 31

Genetic Explanation of schizophrenia: Adoption Studies

Answer 31

Finnish adoptive family study by Pekka Tienari:

Adopted away children of biological mothers with schizophrenia had a risk of 9.4%

Question 32

Genetic Explanation of schizophrenia: Association Studies

Answer 32

Stephen Ripke (2014)
Compared genotypes of 36,989 people with schizophrenia and 113,075 no affected people. Found 108 separate genetic variations were associated with increased risk of schizophrenia